Pushbutton switch with momentary contact action



Oct. 15, 1957 s, WOQDWARD 2,810,027

PUSHBUTTON SWITCH WITH MOIIENTARY CONTACT ACTION Filed March 20, 1957f/n e/rfafl Sfewar/ 4. Mada/am J flap/zzndzw/i Af/omg United StatesPatent 01 PUSHBUT TON SWITCH WITH MOMENTARY CONTACT ACTION Stewart A.Woodward, Stratford, Conn., assignor to General Electric Company, acorporation of New York Application March 20, 1957, Serial No. 647,275

4 Claims. (Cl. 200-5) The present invention relates to a multiplepushbutton switch of the type which includes a plurality of pushbuttonsfor actuating sliders to effect the closing of one or more pre-selectedelectrical circuits when one of the buttons is depressed, whilepreventing the simultaneous operation of a second pushbutton through asuitable interlocking mechanism. This invention is particularlyconcerned with providing one of the buttons of such a switch with amomentary contact action.

This invention is an improvement in the basic pushbutton switch patentof Andrews No. 2,431,904 which is assigned to the same assignee as isthe present invention. Likewise, it is an improvement over a co-pendingHutt application Serial No. 538,031 entitled Detent Means for aPushbutton Switch filed on October 3, 1955, and likewise assigned to thesame assignee as in this invention.

Pushbutton switches of this general type have been used for many yearsfor controlling the heating elements of electric ranges. Some electricranges have an incandescent light in the oven section and a fluorescentlight in the backsplash for illuminating the top of the range. Hence, itis desirable to have a pushbutton switch for controlling these lamps soas to blend with the other pushbutton switches that are visible on thebacksplash. The function of the control switch for a fluorescent lamp isto complete a separate circuit through the lamp so that a preheatcurrent can flow through the filament cathodes and heat themmomentarily. The ballast in the main circuit limits the current flowthrough the cathode fila- Inents; otherwise, they might be heated almostinstantaneously like an ordinary filament lamp. After a few seconds thestarter circuit is opened and the lamp lights. Manual starters of thistype are oftentimes used for desktype fluorescent lamps.

Accordingly, the principal object of this invention is to provide amultiple pushbutton switch with a novel momentary contact action.

A further object of this invention is to utilize the detent mechanism ofa pushbutton switch so that it will provide one of the buttons with amomentary contact action.

A still further object of this invention is to provide a multiplepushbutton switch with a detent mechanism that cooperates with amodified slider to provide a button with a momentary contact action.

The present invention is an improvement over a copending application ofHutt, Serial No. 538,031 previously mentioned. Both this and the Huttapplication have the following switch structure in common. They bothhave a hollow housing of insulating material, stationary contactssecured in the housing, and movable contacts in the form of cantileverspring strips cooperatively associated with the stationary contacts. Aplurality of sliders are arranged longitudinally within the housing inside-by-side relationship and below the spring strips so fliat they areseated on the bottom wall of the housing. Each slider is provided withone or more camming surfaces on its upper edge for alternately engagingcertain of the said spring strips to effect the opening and closing ofthe ice respective contacts in a predetermined manner. A series ofdiagonal working surfaces are likewise formed in each slider to begenerally in alignment with, but distinct from, similar working surfacesin the other slider. A plurality of pushbuttons project into the housingand are associated with the diagonal working surfaces of the sliders.Hence, by depressing one of the buttons the innermost end of that buttonwill engage the diagonal working surfaces of the sliders and shift oneor more of the sliders to change the circuit arrangement of the switch.In addition, a pair of detent pins extend through additional openings inthe sliders there being one pin above the other, while the ends of thepins are confined in a pair of opposed grooves formed in the switchhousing. These pins are biased apart by one or more spring members, andthe lower edge of at least one of the said openings in the sliders isprovided with a cam surface which the pins must override against theresistance of the springs before that slider may shift. The specificinvention disclosed herein involves this same detent mechanism andconcerns the shape of the openings in the sliders that cooperate withthe detent pins. One or both of the top and bottom edges of the slideropenings which lie generally parallel with the axis of movement of thesliders has a special shape to insure the proper movement of thesliders. In the preferred embodiment of my invention illustrated in theaccompanying drawing, the lower edge of an opening in one of the slidershas a pair of spaced pin-receiving pockets that are separated by araised portion, there being an inclined surface extending from one ofthe pockets to provide the desired momentary contact action. One of thepinreceiving pockets represents one extreme at-rest position, While thesecond pocket is the other at-rest position. However, when the momentarycontact button is depressed the slider will shift to such a positionthat the lower detent pin will ride up the said inclined surface againstthe resistance of the detent springs. However, when that button isreleased, the spring will force the lower pin down the inclined surfaceby shifting the slider until it comes to rest in the nearestpin-receiving pocket. While I have chosen to illustrate my invention asincluding a special shape for the momentary contact action, it should berecognized that other modifications could be made operating on the sameprinciple as I have suggested. For instance, there could be twooppositely inclined surfaces separated by a pin-receiv- 1ng pocket togive the switch two momentary contact actions. My invention will bebetter understood from the following description taken in connectionwith the accompanying drawing and its scope will be pointed out in theappended claims.

In the drawing:

Figure 1 is a top plan view of a pushbutton switch embodying myinvention with a portion of the cover removed so that some of the switchparts may be identified.

Figure 2 is a transverse cross-sectional view taken on the lines 22 ofFigure 1.

Figure 3 is a partial cross-sectional side elevational view taken on thelines 3-3 of Figure 1 showing clearly the detent mechanism of thisswitch.

Figure 4 is a partial exploded isometric view of a portion of thesliders showing the pair of detent pins and the C-shaped spring membersof strip material for biasing them apart.

Figure 5 is a diagrammatic view showing the position of the sliders andthe movable and fixed contacts when the central Ofi button is depressed.

Figure 6 is another diagrammatic showing similar to that of Figure 5when the left hand momentary contact button is held down.

-Referring in detail to the drawing, and in particular to Figures l3,represents a hollow switch housing comprising a molded base 11 ofsuitable insulating material and a thin insulating cover plate 12 whichis fastened by screw means 13 that threads into the base to complete theassembly. The base is recessed with a deep longitudinal central cavity14 and relatively shallow side cavities forming shelves 15 and 16. Fixedcontacts 17 are mounted on shelf 16 of the base while spring strips orblades 18 which form the movable contacts of the switch are fastened atone end to terminals 19 that extend through the shelf 15 and outwardlyof the housing, as is best seen in Figure 2.

The movable contacts 18 are normally biased into engagement with thefixed contacts 17. The positions of the movable contacts are controlledby a pair of sliders 22 and 23 of insulating material as is best seen inFigures 5 and 6. The top edge of each slider is formed with a pattern ofraised cam surfaces 24 which are adapted to hold the movable contactsaway from the fixed contacts. Looking at Figure 5, it will be understoodthat all of the movable contacts 18 are in the open position since theyall rest on a cam surface 24 of the sliders. However, this is not truein Figure 6 where the left-hand movable contact 18 is disposed betweentwo raised cam surfaces 24 and hence, the movable contact is allowed tomake engagement with the fixed contact 17.

The present invention is shown embodied in a threeposition switch havingthree pushbuttons 28, 29 and 3!) which are molded of suitable insulatingmaterial with a lower end that is bifurcated as at 31 in Figure 2 tostraddle the two sliders 22 and 23. Each slider is provided with aseries of three openings generally designated as 32 having differentcombinations of vertical and diagonal working surfaces 33 and 34,respectively There is such an opening 32 in each slider for eachpushbutton and hence there are six openings in all. They are generallyin alignment as may be visualized in the diagrammatic showings ofFigures 5 and 6 so that a pin 35 which is carried by the bifurcated endof each button may extend through the sliders for cooperation with thebefore-mentioned diagonal working surfaces 34. Such pins 35 are guidedat their ends in vertical grooves 36 on opposite sidewalls of thecentral cavity 14 of the base. When the cover 12 is fasten-ed over thebase, the pushbuttons 28% extend through close-fitting openings in thecover so that the buttons are guided for straight-line movement by boththe pins 35 and the cover 12. It is well to furnish means to prevent thesliders from rising off of the floor of the base ill. This function isprovided by an L-shaped spring clip 37 shown in Figures 1 and 2 asoverlying the sliders at each end with an upwardly extending portion 38that is confined in the notch 39 of the base so that the clips will beheld down by the cover plate 12 and in turn they will hold the slidersdown.

The structure which has been described above is conventional and merelya modification of the teachings of the beforementioned Andrews PatentNo. 2,431,904. This invention involves the addition of a mechanism whichwill not allow the left hand momentary contact button 28 of Figure 6 tostay down when the manual force is released. This mechanism is bestshown in Figure 4 where the two sliders 22 and 23 are shown in part. Forillustration purposes the positions of the two sliders have beenreversed in Figure 4. Each slider 22 and 23 contains a fourth openingindicated as 411 in slider 22 and 41 in slider 23. The opening 41 isgenerally square in shape, while the opening has a similar configurationexcept for the lower edge. This lower edge has several portions, namely,two pin receiving pockets 42 separated by a raised can't surface 43 andan upwardly inclined corner surface 44-.

A pair of detent pins 4-5 are arranged to extend through the openings44) and 41 of the sliders and to be confined in vertical grooves 46 inthe base as seen in Figure 1, similarly to the grooves 36. A pair ofidentical spring members 47 of generally C-shape are arranged betweenthe ends. of the vertically spaced pins 45 to normally bias them apart.The two ends of each spring 47 first converge towards each other as at48 and then turn at about degrees to diverge away from each other as at49. These surfaces 48 and 49 form recesses 50 therebetween so that thespring 47 may clip onto the pins 45 and not become disengaged easily.These detent pins 45 and spring members 47 are similar in nature to thedetent mechanism of a co-pending application to Hutt Serial. No. 538,031mentioned previously.

Now turning to a consideration of Figure 5, the middle or Off button 29is depressed so that all of the movable contacts 18 are open and out ofengagement with the fixed contact 17. The button 28 is the momentarycontact button and when it is depressed and held down as shown in Figure6 slider 22 will shift to the left while slider 23 remains in place. Asslider 22 is moving to the left the lower detent pin 45 must ride overthe raised cam surface 43 and ultimately climb up the inclined surface44. However, in so doing the springs 47 must be compressed which tendsto retard the movement of the slider and build potential energy in thesprings which will be released when the manual force holding the buttondown is released. Once the hand is removed from the button 23 the detentpins will separate due to the expansion of the springs 47 until thelower pin 45 engages in the nearest pin-receiving pocket 42. Then theswitch is at rest and the button 28 is in intermediate position betweenfully opened and fully closed. It is this particular nature of theopening 40 in the slider 22 which provides the unobvious result of amomentary contact action in a multiple pushbutton switch.

Having described above my invention of a multiple pushbutton switch witha novel momentary contact action as well as a detent action, it will bewell understood by those skilled in this art that this improvement hasbeen made by adapting a detent mechanism to perform the additionalfunction of a momentary contact action. I have accomplished this withlittle or no increase in cost of manufacturing and with an easy methodof assembly and fabrication. While I have chosen to illustrate myinvention showing the opening of the slider as having a unique loweredge it will be well understood by those skilled in this art that thesame edge could be duplicated at the top of the slider so as to make theopening symmetrical about the horizontal axis. Alternatively, the noveledge could be only at the top edge. This invention is not limited toembodiments having a pair of pin-receiving pockets but othermodifications may suggest themselves to those skilled in this art. Forinstance, the edge might include two oppositely inclined surfaces thatare separated by a pin-receiving pocket.

Modifications of this invention will occur to those skilled in this artand it is to be understood, therefore, that this invention is notlimited to the particular embodiments disclosed, but that it is intendedto cover all modifications which are within the true spirit and scope ofthis invention.

What I claim is new and desire to secure by Letters Patent of the UnitedStates is:

l. A multiple pushbutton switch comprising a hollow housing, contactmeans arranged in the housing including fixed contacts and movablecontacts, a plurality of sliders having camrning surfaces that actuatethe movable contacts, a series of diagonal working surfaces formed oneach of the sliders, and means for actuating the sliders comprising aplurality of pushbuttons projecting into the housing and guided forstraight-line movement, each button having an inner portion forengagement with selected ones of the aligned working surfaces as thebutton is depressed to move said sliders to predetermined contactcontrolling positions, and detent means for retarding the movement ofthe sliders, there bein' an opening of generally square shape in atleast one of the sliders, the lower edge of the opening defining twospaced pockets separated by a raised portion, and an upwardly inclinedcorner surface communicating with one of the said pockets, aspringbiased detent pin extending through the sliders and guided forreciprocating movement by fixed wall members of the switch housing, thepin being biased against the lower edge of the said slider openingswhereby the force of the spring must be overcome before the slider mayshift as a button is depressed, the switch being provided with amomentary contact action for at least one of the buttons whereby thedetent pin will not remain in place on the inclined corner surface whenthe related button is released but will be pressed downwardly by itsspring and thereby shift the slider to open the previously closedmovable contact.

2. A multiple pushbutton switch as recited in claim 1 wherein there aretwo detent pins, one above the other and biased apart by a pair ofspring members one at each side of the group of sliders, the bottom pinbeing adapted to engage the lower edge of the said slider opening.

3. A multiple pushbutton switch as recited in claim 2 wherein each ofthe said pair of springs is of nearly closed C-shape with diverging endportions that engage the detent pins and hold the springs assembledtherewith.

4. A multiple pushbutton switch comprising a hollow housing, contactmeans arranged in the housing including fixed contacts and movablecontacts that are operated by camming surfaces on a plurality ofsliders, a series of diagonal working surfaces formed on each of thesliders, and means for actuating the sliders comprising a plurality ofpushbuttons projecting into the housing, each button having an innerportion for engagement with selected ones of the diagonal workingsurfaces as one of the buttons is depressed to move said sliders topredetermined contact controlling position, and detent means for atleast one of the sliders comprising an opening in said slider forreceiving a pair of detent pins whose ends are guided in opposed slotsformed in the housing on opposite sides of the group of sliders, oneedge of the opening that is generally parallel with the axis along whichthe slider moves having an inclined surface that is engaged by one ofthe detent pins, and spring means biased between the two detent pins toforce them apart so that one pin will be resiliently biased against thesaid inclined surface, the said edge of the slider opening having inaddition two spaced pockets for indexing the detent pin and hence, theslider for proper positioning of the slider.

References Cited in the file of this patent UNITED STATES PATENTS

